The ultimate goal of this application is to enhance our ability to answer, reliably and efficiently, critical questions in the treatment of cancer. Because randomized clinical trials provide the best evidence of the effectiveness of cancer treatments, the National Cancer Institute funds a Clinical Trials Cooperative Group Program through the Clinical Investigations Branch of the Cancer Therapy Evaluation Program. In the past few years, substantial changes have been made to the Clinical Trials Program in order to promote the more rapid development and completion of studies that address important issues in cancer treatment. These changes have had a major impact on the conduct of cooperative clinical trials throughout North America, including Canada. The National Cancer Institute of Canada, an agency funded by donations to the Canadian Cancer Society, supports a national clinical trials group (NCIC CTG) that functions similarly to US groups. Since 1988, the NCIC CTG has been funded by NIH to support the Group's contribution to trials that involve a collaborative effort between two or more groups - "intergroup" trials. The purpose of this application is to renew and expand that funding in a manner that will allow the NCIC CTG to participate actively in the "New National System" of clinical trials. The specific aims of the proposal are the same as they were in our initial application; namely: 1. To contribute patient enrolment, data management resources, and high quality data to intergroup trials sponsored by NCI; 2. To provide scientific input into the development, design and conduct of NCI intergroup trials; and 3. To provide leadership and coordination resources for some NCI intergroup trials. However, because of the work supported by this award in the past five years and the changes in the clinical trials system, the emphasis of this application is on our role a leader of large North American studies.